硕士论文-SiC半导体表面处理技术研究.pdf

大连理工大学
硕士学位论文
SiC半导体表面处理技术研究
姓名:王海波
申请学位级别:硕士
专业:物理电子学
指导教师:王德君
20071220
大连理工大学硕士学位论文
摘要
氢钝化技术是利用氢原子终结表面悬挂键的一种技术。半导体经氢钝化处理后可以
获得于净、平整、抗氧化能力强的表面,有利于制备高性能的MOS结构和欧姆接触。
由于Sic表面存在极性键,传统的混法氢钝化技术并不适合SiC。常压氢气退火或RF
等离子体处理方法中,为了使氢气有效热解,需要1000C或650℃的高温。而且温度越
高氢的表面覆盖率越低。
本论文利用ECR等离子体系统,探索了低温氢等离子体处理SiC的工艺条件;研
究了低温氢等离子体处理对SiC表面化学结构和抗氧化能力的影响:研究了低温氢等离
子体处理对MOS电容器件和欧姆接触的影响。实验结果表明,低温200℃处理12分钟
后,SiC表面出现最佳处理效果。随着处理时间增加,处理效果变差,其原因是随着处理
时间的增加,SiC表面遭到了氢等离子体破坏。当处理温度提高时,处理时间变短。在
300C处理5分钟后出现最佳处理效果,在400℃处理4分钟后出现最佳处理效果,在
500℃处理2分钟后出现最佳处理效果。虽然处理时间随着处理温度的升高不断降低,
但处理效果逐渐变差,其原因是表面氢覆盖率随着温度的升高不断下降; RHIEBD分析
发现,经低温氢等离子体处理12分钟后,SiC表面变为了(1x1)非重构相。XPS分析
发现,传统湿法RCA处理后的SiC表面存在C的污染物。在200℃下经氢等离子体处
理12分钟后,C的污染物消失。暴露在空气中10分钟后(装样时间),经等离子体处
理的SiC表面O/Si的含量明显低于传统湿法RCA清洗的O/Si的含量。暴露在空气中3
小时后,经等离子体处理的SiC表面O/Si的含量无明显变化,表现出明显的抗氧化性
在低温氢等离子体处理后的SiC上制备了MOS电容器件和欧姆接触,分析发现
经氢等离子体预处理的MOS电容器件界面忞密度明显低于传统湿法处理后 Sic MOS电
容器件,达到了6x10cm2ev'数量级:经低温等离子体处理的SiC在退火前就可形成
良好的欧姆接触,大大降低了工艺难度。
关键词:SiC;ECR; RHEED;XPS;R
大连理工大学硕土学位论文
Study on SIC Surface Treatment Technology
Abstract
The hydrogen passivation is a technology that make hydrogen atoms passivate the surface
dangling bonds. hydrogen passivation technology can yield the cleanin -flat semiconductor
surface, which has good anti-oxidation Capability. It is benefit to make high performent MOS
devices and ohmic contacts. However, because there are polar bonding on Sic surface,
Tradditional wet hydrogen passivation technology is not fit for Sic. In the hydrogen
annealing technology or RF hydro en plasma cleanin technolgy, It needs 1000 or 650C
high tempreture to decompose hydro en molecula, It finds that the higher the temperature is,
the lower the coverage is
The surfaces of Sic are cleaned by hydrogen with ECR-PEMOCVD and the best
technological conditions are studied. The structure of Sic surfaces composition, the
contamination removing and the resisting oxidation of Sic surface are studied. The effects of
hydrogen plasma on the MOS devices and ohmic contact are studied.It finds that aft
cleaned by hydrogen plasma for 12 minutes at 200C, he surface of Sic shows the best effect
and it becomes bad with the time increases. when it is 18 minutes, the picture of Sic RHEED
becomes blurry. It is because that the surface of Sic is destroied by hydrogen plasma as the
time increases. when the temperature increases, the time reduces, At 300C,it is 5 minutes that
it got the best effect. At 400C, it is 4 minutes that it got the best effect. at 500 C, it is 2 minutes
that got the best effect. Although the time is reduced, the cleaning effect become bad as the
temperature increases. It finds by RHEED that after cleaned by hydrogen plasma at 200C for
12 minutes, the surface of Sic show(11 )phase. It finds by XPS that there are the C/CH
contaminations on Sic sur ace after the traditional RCA cleaning. After cleaned by hydrogen
plasma for 12 minutes at 20, they disappears. The intensity of Siox for the Sic surface
cleaned by RCA is higher than by hydrogen plasma for 12 minutes at 200C
We make MOS device on the Sic which cleaned by hydrogen plasma for 12 minutes at
200C.It shows that the intensity of interface State for the Sic which is cleaned by hydrogen
plasam is lower th